Electron paramagnetic resonance measurements were performed on samples of float-zone material that had been implanted with Er to a dose of 1015/cm2. One sample was also co-implanted with O to give concentrations of 1020/cm3 and 1019/cm3 for O and Er, respectively. In the case of the co-implanted sample, sharp lines were observed which were attributed to a single spin 1/2 Er3+ center with a g tensor that exhibited monoclinic C1h symmetry. In the absence of O, sharp lines were not observed. No Er3+ cubic centers were detected in either sample.

J.D.Carey, J.F.Donegan, R.C.Barklie, F.Priolo, G.Franzò, S.Coffa: Applied Physics Letters, 1996, 69[25], 3854-6